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Martin KaFai Lau dda770407b Merge branch 'Update and document struct_ops' 
David Vernet says:

====================
The struct bpf_struct_ops structure in BPF is a framework that allows
subsystems to extend themselves using BPF. In commit 68b04864ca
("bpf: Create links for BPF struct_ops maps") and commit aef56f2e91
("bpf: Update the struct_ops of a bpf_link"), the structure was updated
to include new ->validate() and ->update() callbacks respectively in
support of allowing struct_ops maps to be created with BPF_F_LINK.

The intention was that struct bpf_struct_ops implementations could
support map updates through the link. Because map validation and
registration would take place in two separate steps for struct_ops
maps managed by the link (the first in map update elem, and the latter
in link create), the ->validate() callback was added, and any struct_ops
implementation that wished to use BPF_F_LINK, even just for lifetime
management, would then be required to define both it and ->update().

Not all struct_ops implementations can or will support update, however.
For example, the sched_ext struct_ops implementation proposed in [0]
will not be able to support atomic map updates because it can race with
sysrq, has to cycle tasks through various states in order to safely
transition, etc. It can, however, benefit from letting the BPF link
automatically evict the struc_ops map when the application exits (e.g.
if it crashes).

This patch set therefore:

1. Updates the struct_ops implementation to support default values for
   ->validate() and ->update() so that struct_ops implementations can
   benefit from BPF_F_LINK management even if they can't support
   updates.
2. Documents struct bpf_struct_ops so that the semantics are clear and
   well defined.
---
v2: https://lore.kernel.org/bpf/0f5ea3de-c6e7-490f-b5ec-b5c7cd288687@gmail.com/T/
Changes from v2 -> v3:
- Add patch 2/2 that documents the struct bpf_struct_ops structure.
- Add Kui-Feng's Acked-by tag to patch 1/2.

v1: https://lore.kernel.org/lkml/20230811150934.GA542801@maniforge/
Changes from v1 -> v2:
- Move the if (!st_map->st_ops->update) check outside of the critical
  section before we acquire the update_mutex.
====================

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
2023-08-14 22:23:47 -07:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-08-10 18:59:43 -07:00
block block-6.5-2023-07-21 2023-07-22 11:05:15 -07:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto crypto: algif_hash - Fix race between MORE and non-MORE sends 2023-07-08 22:48:42 +10:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-08-10 18:59:43 -07:00
drivers tun: avoid high-order page allocation for packet header 2023-08-10 19:33:35 -07:00
fs two ksmbd server fixes 2023-08-09 21:12:56 -07:00
include bpf: Document struct bpf_struct_ops fields 2023-08-14 22:23:39 -07:00
init Kbuild updates for v6.5 2023-07-01 09:24:31 -07:00
io_uring io_uring-6.5-2023-07-28 2023-07-28 10:19:44 -07:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel bpf: Support default .validate() and .update() behavior for struct_ops links 2023-08-14 22:23:39 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-08-10 14:10:53 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: Fix access_remote_vm() regression on tagged addresses 2023-08-09 08:05:23 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-08-10 14:10:53 -07:00
rust rust: fix bindgen build error with UBSAN_BOUNDS_STRICT 2023-08-04 17:10:50 +02:00
samples samples/bpf: README: Update build dependencies required 2023-07-18 17:29:43 -07:00
scripts x86: 2023-07-30 11:19:08 -07:00
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-08-10 14:10:53 -07:00
sound ASoC: Fixes for v6.5 2023-07-27 14:54:23 +02:00
tools selftests/bpf: Add various more tcx test cases 2023-08-14 21:54:59 -07:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Grab a reference to KVM for VM and vCPU stats file descriptors 2023-07-29 11:05:28 -04:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Revert ".gitignore: ignore *.cover and *.mbx" 2023-07-04 15:05:12 -07:00
.mailmap mailmap: update remaining active codeaurora.org email addresses 2023-07-27 13:07:05 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS - Address -Wmissing-prototype warnings 2023-06-26 16:43:54 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-08-10 14:10:53 -07:00
Makefile Linux 6.5-rc5 2023-08-06 15:07:51 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.